1. Field of the Invention
The present invention is concerned with a carrier system for carrying silicon wafers accomodated in a cassette in or out of a processing device or a measuring device.
2. Prior Art
In the case of measuring effecting a variety of processings on the silicon wafers or measuring the performance thereof by means of a measuring device, the silicon wafers are carried within a clean room while being accomodated in a shelf type cassette. The silicon wafers together with the cassette are brought close to the processing device or the measuring device, in which place the silicon wafers are taken out of the cassette to be transferred onto a stage of the processing device or the like.
As a conventional carrier system for carrying both the cassette and the wafers within the clean room, a belt conveyor type device has already been put into practical use. However, since such a device is incapable of moving vertically or laterally, a cassette elevator for moving the cassette up and down is required. In addition, placement of the processing device is confined, and it is necessary to separately install the devices for carrying the cassette and the wafers. This induces to problems wherein the costs of equipments increase and a space formed within the clean room is narrowed.